The function of commercially available glass or glass ceramic cooktops for cooking wells or stoves is limited predominantly to heating and keeping warm the food to be cooked. The cooking zones are controlled with energy regulators which are operated as automatic regulators with optional temperature or time control. Furthermore, the cooking zones are equipped with induction loops for automatic pot detection or pot size detection in the case of multicircuit heaters.
Cooktop also exist in which functional elements, such as operating and display elements, are integrated into the cooking surface. Thus the aforementioned document includes a functional element in the form of a manual switch installed in an opening in the cooking surface. The opening is sealed with a permanently elastic silicone adhesive in the manner of a diaphragm, flush with the surface of the cooktop. This defines an operational zone. This operational zone sealed with silicone has the requisite is sufficiently flexible so that the switch mounted below is manually operable.
Conventionally, the operational zone is made of a material which is different from that of the cooking surface. Therefore, the operational zone is in sharp visual contrast with the cooking surface, a feature that can have a negative effect on the overall appearance of the appliance. Furthermore, in the known case, only recesses of the cooking surface with a small dimension can be bridged, i.e. the integration of functional elements is limited with respect to the choice of type. Therefore, functions and processes related to the cooking operation have to be done separately by the operating personnel. In particular, the weighing of food has to be done on a separate scale. Similarly, cooking recipes have to be found in a cook book. This means more time and space is needed in the kitchen.
Therefore, the present invention is based on the problem of integrating functions and processes accompanying the cooking process, such as control and weighing functions and recipe display, into the cooktop with an visually appealing look without spatially limiting the operational zone.
This problem is solved by the invention in that the operational zone is formed by a part that is made of a hard material and that is embedded into the recess of the cooking surface by means of a thermally stable sealing connection that compensates for the different coefficients of thermal expansion.